关键词：
CaAFR1;CaMYB61;Khib;cellulose and hemicellulose;histone deacetylases;stem lodging
摘要：
Plant stems constitute the most abundant renewable resource on earth. The function of lysine (K)-2-hydroxyisobutyrylation (K(hib)), a novel post-translational modification (PTM), has not yet been elucidated in plant stem development. Here, by assessing typical pepper genotypes with straight stem (SS) and prostrate stem (PS), we report the first large-scale proteomics analysis for protein K(hib) to date. K(hib)-modifications influenced central metabolic processes involved in stem development, such as glycolysis/gluconeogenesis and protein translation. The high K(hib) level regulated gene expression and protein accumulation associated with cell wall formation in the pepper stem. Specially, we found that CaMYB61 knockdown lines that exhibited prostrate stem phenotypes had high K(hib) levels. Most histone deacetylases (HDACs, e.g., switch-independent 3 associated polypeptide function related 1, AFR1) potentially function as the "erasing enzymes" involved in reversing K(hib) level. CaMYB61 positively regulated CaAFR1 expression to erase K(hib) and promote cellulose and hemicellulose accumulation in the stem. Therefore, we propose a bidirectional regulation hypothesis of "K(hib) modifications" and "K(hib) erasing" in stem development, and reveal a novel epigenetic regulatory network in which the CaMYB61-CaAFR1 molecular module participating in the regulation of K(hib) levels and biosynthesis of cellulose and hemicellulose for the first time.
摘要：
<jats:p>Potato common scab, caused mainly by <jats:italic>Streptomyces scabies</jats:italic>, causes surface necrosis and reduces the economic value of potato tubers, but effective chemical control is still lacking. In this study, an attempt was made to control potato common scab by inoculating potatoes with <jats:italic>Bacillus velezensis</jats:italic> (<jats:italic>B. velezensis</jats:italic>) and to further investigate the mechanism of biological control. The results showed that <jats:italic>B. velezensis</jats:italic> Y6 could reduce the disease severity of potato common scab from 49.92 ± 25.74% [inoculated with <jats:italic>Streptomyces scabies</jats:italic> (<jats:italic>S. scabies</jats:italic>) only] to 5.56 ± 1.89% (inoculated with <jats:italic>S. scabies</jats:italic> and Y6 on the same day) and increase the potato yield by 37.32% compared with the control under pot experiment in this study. Moreover, in the field trial, it was found that Y6 could also significantly reduce disease severity from 13.20 ± 1.00% to 4.00 ± 0.70% and increase the potato yield from 2.07 ± 0.10 ton/mu to 2.87 ± 0.28 ton/mu (<jats:italic>p</jats:italic> &lt; 0.01; Tukey’s test). Furthermore, RNA-seq analysis indicated that 256 potato genes were upregulated and 183 potato genes were downregulated in response to <jats:italic>B. velezensis</jats:italic> Y6 inoculation. In addition, strain Y6 was found to induce the expression of plant growth-related genes in potato, including cell wall organization, biogenesis, brassinosteroid biosynthesis, and plant hormone transduction genes, by 1.01–4.29 times. As well as up-regulate hydroquinone metabolism-related genes and several transcription factors (bHLH, MYB, and NAC) by 1.13–4.21 times. In summary, our study will help to understand the molecular mechanism of biological control of potato common scab and improve potato yield.</jats:p>
摘要：
<jats:p>In various plant species, many transcription factors (TFs), such as MYB, bHLH, and WD40, have been identified as regulators of anthocyanin biosynthesis in underground organs. However, the regulatory elements of anthocyanin biosynthesis in the tuberous roots of sweet potato have not been elucidated yet. Here, we selected the purple-fleshed sweet potato cultivar “Zhezi1” (ZZ<jats:italic><jats:sup>P</jats:sup></jats:italic>) and its spontaneous yellow-fleshed mutant “Xinli” (XL<jats:italic><jats:sup>Y</jats:sup></jats:italic>) to investigate the regulatory mechanism of the anthocyanin biosynthesis in the tuberous roots of sweet potato. By analyzing the <jats:italic>IbMYB1</jats:italic> genotype in ZZ<jats:italic><jats:sup>P</jats:sup></jats:italic> and XL<jats:italic><jats:sup>Y</jats:sup></jats:italic>, we found that the <jats:italic>IbMYB1-2</jats:italic>, a MYB TF involved in anthocyanin biosynthesis, was missing in the XL<jats:italic><jats:sup>Y</jats:sup></jats:italic> genome, which might lead to an extreme decrease in anthocyanins in XL<jats:italic><jats:sup>Y</jats:sup></jats:italic>. A comparative transcriptome analysis of ZZ<jats:italic><jats:sup>P</jats:sup></jats:italic> and XL<jats:italic><jats:sup>Y</jats:sup></jats:italic> was conducted to find the TFs involved in anthocyanin biosynthesis in ZZ<jats:italic><jats:sup>P</jats:sup></jats:italic> and XL<jats:italic><jats:sup>Y</jats:sup></jats:italic>. The anthocyanin structural genes were significantly enriched among the differentially expressed genes. Moreover, one MYB activator (<jats:italic>IbMYB1</jats:italic>), one bHLH (<jats:italic>IbbHLH2</jats:italic>), three WRKY activator candidates (<jats:italic>IbWRKY21</jats:italic>, <jats:italic>IbWRKY24</jats:italic>, and <jats:italic>IbWRKY44</jats:italic>), and two MYB repressors (<jats:italic>IbMYB27</jats:italic> and <jats:italic>IbMYBx-ZZ</jats:italic>) were highly expressed in ZZ<jats:italic><jats:sup>P</jats:sup></jats:italic> accompanied with anthocyanin structural genes. We also tested the expression of these TFs in six purple- and two orange-fleshed sweet potato cultivars. Interestingly, most of these TFs were significantly positively correlated with anthocyanin contents in these cultivars. The function of the anthocyanin biosynthesis repression of <jats:italic>IbMYB27</jats:italic> and <jats:italic>IbMYBx-ZZ</jats:italic> was verified through transient co-transformation with <jats:italic>IbMYB1</jats:italic> into tobacco leaves. Further functional verification of the above TFs was conducted by Y2H, BiFC, and dual-luciferase assays. These tests showed that the MYB-bHLH-WD40/MYB-bHLH-WD40-WRKY complex activated the promoter of anthocyanin structural gene <jats:italic>IbDFR</jats:italic> and promoters for <jats:italic>IbWRKY44</jats:italic>, <jats:italic>IbMYB27</jats:italic>, and <jats:italic>IbMYBx-ZZ</jats:italic>, indicating reinforcement and feedback regulation to maintain the level of anthocyanin accumulation in the tuberous roots of purple-fleshed sweet potato. These results may provide new insights into the regulatory mechanism of anthocyanin biosynthesis and accumulation in underground organs of sweet potatoes.</jats:p>
摘要：
Potato (Solanum tuberosum L.) is an important staple food worldwide. However, its growth has been heavily suppressed by salt stress. The molecular mechanisms of salt tolerance in potato remain unclear. It has been shown that the tetraploid potato Longshu No. 5 is a salt-tolerant genotype. Therefore, in this study we conducted research to identify salt stress response genes in Longshu No. 5 using a NaCl treatment and time-course RNA sequencing. The total number of differentially expressed genes (DEGs) in response to salt stress was 5508. Based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, it was found that DEGs were significantly enriched in the categories of nucleic acid binding, transporter activity, ion or molecule transport, ion binding, kinase activity and oxidative phosphorylation. Particularly, the significant differential expression of encoding ion transport signaling genes suggests that this signaling pathway plays a vital role in salt stress response in potato. Finally, the DEGs in the salt response pathway were verified by Quantitative real-time PCR (qRT-PCR). These results provide valuable information on the salt tolerance of molecular mechanisms in potatoes, and establish a basis for breeding salt-tolerant cultivars.
摘要：
Tubers are vegetative reproduction organs formed from underground extensions of the plant stem. Potato tubers are harvested and stored for months. Storage under cold temperatures of 2-4 degrees C is advantageous for supressing sprouting and diseases. However, development of reducing sugars can occur with cold storage through a process called cold-induced sweetening (CIS). CIS is undesirable as it leads to darkened color with fry processing. The purpose of the current study was to find differences in biological responses in eight cultivars with variation in CIS resistance. Transcriptome sequencing was done on tubers before and after cold storage and three approaches were taken for gene expression analysis: 1. Gene expression correlated with end-point glucose after cold storage, 2. Gene expression correlated with increased glucose after cold storage (after-before), and 3. Differential gene expression before and after cold storage. Cultivars with high CIS resistance (low glucose after cold) were found to increase expression of an invertase inhibitor gene and genes involved in DNA replication and repair after cold storage. The cultivars with low CIS resistance (high glucose after cold) showed increased expression of genes involved in abiotic stress response, gene expression, protein turnover and the mitochondria. There was a small number of genes with similar expression patterns for all cultivars including genes involved in cell wall strengthening and phospholipases. It is proposed that the pattern of gene expression is related to chilling-induced DNA damage repair and cold acclimation and that genetic variation in these processes are related to CIS.
关键词：
Cd distribution;Cd-safe tubers;Phytoremediation;Potato (Solanum tuberosum L.)
摘要：
Cadmium (Cd) is a toxic element that can accumulate in plants and poses a threat to human health through biomagnification. There are differences in Cd levels among different plants tissues. Hence, an optimal crop that possesses low Cd levels in the edible parts but high levels in the inedible parts is urgently needed to simultaneously lower soil-Cd levels in contaminated fields and to produce Cd-safe crops. In this study, we investigated the Cd levels in tubers and other tissues of potato (Solanum tuberosum L.) using different experimental approaches, and identified variations in Cd accumulation in different potato cultivars and characterized the Cd-distribution pattern in potato. Our results showed that Cd accumulation in tubers of the tested cultivars varied greatly, and that tuber-Cd levels were much lower than in the stems or leaves. Two-way ANOVA revealed that the tuber-Cd levels in potato are determined by both genotypic differences and the soil-Cd levels of the farmlands. Among the cultivars tested, one cultivar, 'Eshu10', was found to have the lowest tuber-Cd levels but had much higher Cd levels in leaf and stem tissues. Our study shows that the Cd-distribution pattern within potato plants makes it an ideal candidate for the safe production of a staple food that also has the potential to contribute to the remediation of contaminated soils. (C) 2019 Elsevier B.V. All rights reserved.
